Masonry joint



Now-'25, 1941. A. J. BQHN' 2,263,914

'MASONRY JOINT Filed Nov. 4, 1940 INVENTOR W4 gust 1507i ATTORNEYS Patented Nov. 25, 1941 UNITED STATES PATENT OFFICE MASONRY JOINT v 7 August J. Bohn, Atlanta, Ga. 7 Application November 4, 1940, Serial No. 364,132

9 Claims.

This invention relates to the formation of a watertight masonry joint, and, more particularly, to a novel building unit, the masonry joint employing the unit, and the method of making said joint.

As has been well known, the weakest joint in a masonry structure is the vertical joint or the head joint between adjacent building units. It is at this point that the large proportion of leaks occur in the structure because of the separation of the mortar from the building unit due to the contraction of the mortar during the settingv thereof as a result of chemical action in the mortar.

These minute cracks provide passages by which the water and moisture travel through the wall, and it is an object of the present invention to form a building unit and a joint using the building unit which effectively prevents such separation as to permit moisture to pass therethrough,

Prior constructions have provided projections or the like on the ends of the building units in an efiort to provide a battle construction to resist the passage of moisture through the walls. These, however, have been unsuccessful, for while such constructions may increase the path of travel of the moisture, they do not provide the seal or bond between the material of the joint or mortar and the unit necessary to prevent this passage.

According to the present invention, the ends of the building unit are provided with recesses or grooves of substantial depth extending for the full length of the surface from top to bottom. The recesses are of such shape that the walls thereof form a predetermined angle with respect to the end of the brick. This critical angle must be less than the angle formed by the resultant motion of a quarter section of the joint with respect to the center line of the joint.

As the mortar contracts, due to the setting thereof, a volumetric change takes place. This change is a contraction, the amount of which at any point on the surface of the sphere is equal to that at any other point on its surface, and is in a direction toward the center of the sphere. This will cause the mortar in each quarter section to be drawn toward the center.

of the joint. When theaforesaid relation exists, the movement of the mass of mortar toward the center of the joint will causethe face of the mortar joint within the recess to be moved into tight engagement with the wall of the recess and form an effective bond therewith through which the moisture cannot pass.

If the angle of the wall of the recess is greater than the angle formed by the resultant movement of the mass with respect-to the center line of the joint, the contraction will cause the mass of mortar to move away from and separate from the wall of the recess in the building unit as well as from the end of thebuilding unit and although there may be a mechanical interlock at the joint it will permit moisture to flow.

Since the adhesion between the mortar of the joint and the building unit depends to some extent upon the pressure between the surfaces thereof, the movement of the mass into tighten-j gagement with the wall of the recess will serve to produce an improved and better'bond between the mortar and the building unitand eliminate any path through which the moisture may pass.

The building units may be hollow or solid, and may be constructed of clay or shale, concrete or other suitable building material.

In the illustrated form oi the invention, the ends of, the building units are provided with dovetail grooves, although grooves of other con-. figurations, such as circles or other irregular shapes, may be employed so long as theyprovide a wall surface havinga definite angular relation with the end of the building unit, as will satisfy the above requirement.

While in many instances the weight of the building unit will providev suflicient pressure to. compensate for the contraction of the mortar in the horizontal joints and thus tend to reduce the leaks therethrough, if desired, the top and bottom faces of the building unit can be provided with one or more recesses of the type indicated so that the mortar, when contracting and setting, will produce a watertight union therebetween in the same manner as it does between the end sections of the unit.

Other features and advantages will be apparent' from the specification and claims when considered in connection with the drawing, in which:

Figure 1 is a perspective view of a partial wall structure. I a l Fig. 2 is a detail plan view of a section of the joint showing the recess and the relationship existing between the elements of the joint before setting.

Fig. 3 is a diagrammatic view of the quarter section of the joint.

Fig. 4 is a modified building unit in which'the recesses extend on the top and bottom face, as well as the end faces.

Fig. 5 is a detail plan view of a section of the joint having a modified dovetail recess in the building unit.

Fig. 6 is a view similar to Fig. 5 showing a circular recess in the building unit.

A fragment of a masonary structure is shown in Figure 1 in which a wall is made up of a plurality of building units ll of the present invention laid up in courses secured together by horizontal mortar joints I2 and vertical mortar joints I3 which may extend through the wall or which may be broken in the middle as shown in the joint 13.

These building units may be of hollow construction, illustrated in Figure 1, or the solid brick type, shown in Fig. 4. The units may be of tile, concrete blocks, other well-known building units or of brick. j I

In masonry walls, difliculty has been encountered due to the separation of th mortar from the building units as the mortar contracts during etting. In the horizontal mortar joints, the difliculty has not been so great since the bricks can move by gravity into a position in which the separation is a minimum. However, at the ends of the bricks or in the vertical or head joints, the building units cannot so move, and since the cohesion of the mortar is greater than the adhesion of the mortar to the building units, upon contracting, it separates from the building unit and cracks or crevices develop through which the moisture can penetrate.

Since the weakest joint "is present at the head or vertical joint l3 and the greatest difiiculty is encountered with moisture passing through the walls at this joint, the present invention is illustrated as applied to these joints and shows the building units ll provided at each end with recesses or grooves l4 extending from the top to the bottom of the unit. One or more of these recesses can be employed as required. As shown in Fig. 1, two such recesses are formed in each end of the building unit and are so positioned, that, when laid up in a wall, two recesses in the adjacent units will be located opposite one another.

By providing a specific relationship between the shape of the recess and the size of the joint, as will be described, a strong bond between the building unit and the mortar is achieved. This novel bonding is incident to the setting of the mortar, and a substantially watertight joint is obtained. In the building unit illustrated in Figs. 1-3, the recess I4 is dovetail in shape. While dovetail recesses have long been known in building units, they have been used to provide a mechanical interlock between the building units rather than insure a bond between the building unit and the mortar, and, as will be shown, do not of themselves produce the watertight joint as required.

Looking at the joint in greater detail in Fig. 2, it will be seen that it has been separated by dot and dash lines into quarter sections. Inasmuch as volumetric contraction of the joint during setting will produce an equal movement in all directions, the same action will occur in all of the sections. One quarter section S, set offin heavy dot and dash lines, will be described and reference numerals will be applied thereto for the sake of simplicity. y

In this detailed showing, it will be noted that the recess I4 is spaced inwardly from the face l5 of the building unit and opens into the end 16 of the unit and is so shaped that the wall 11 of the recess forms a predetermined angle Awith the end [6 of the brick. The formation of this angle is one of the critical features of the invention, for this angle must not be greater than the angle B in Fig. 3, formed by the line representing the resultant movement of the quarter section S and a line XX passing through the center of the joint, as will be explained.

From the quarter section S shown in detail in Fig. 3, it will be seen that the center of gravity of the sections Sa and Sb are at G and G" respectively, and the centerof gravity of the irregular quarter section will lie on line G'G at G. Since the action of contraction in the mortar joint is similar to that occurring when a spherical mass of mortar contracts, the resultant movement of the mortar mass of the joint, during the setting of the mortar in the joint, will be along a line connecting the center of gravity G with the center of the joint 0. Therefore the line representing the resultant movement of the mass will be 0G. This line forms, with the line passing through the center of joint OX, the angle B. From an inspection of this figure, it will be appar ent that, as the mass moves along the line 0G, its face adjacent the wall I! will be moved inwardly in the direction of arrows P against the wall and the mortar forced into tight engagement therewith during the setting period. The mortar, being in a plastic condition during this movement, will move against the wall with sufficient pressure to improve the adhesion between the mortar and the surface of the building unit. Since the bonding between the wall and the mortar, as above, will occur in each quarter section, this movement will mechanically seal the joint and keep the mortar firmly pressed against the building unit. The mortar in the entire joint will, therefore, be firmly adhered to the adjacent building units with an adhesion that is never broken and assures an impermeable joint.

The difference between the angles A and B shall be such that sufficient pressure is developed between the mortar and the wall of the recess to improve the bonding relation therebetween but insufficient to produce a fracture in the joint itself.

Since the angle B depends upon the location of the center of the joint, it will be seen that the joint 13 must be of a width which will cause the angle B to fulfill the requirements, namely, that it shall be greater than the angle A.

In forming a watertight joint of the present invention, as the courses of brick are laid up, the mortar at the head joint should be laid in so as to completely fill the recess, and the adjoining bricks should be positioned so that the width of the joint satisfies the requirementsof the particular design of the brick.

If the angle A of the building unit is greater than the angle B of the joint, the mortar will draw away from the walls of the recess. Under these conditions, the mechanical interlock between the brick and mortar will still be present, as was-the object of prior recessed buildingunits, nevertheless the opening through the joint will be formed and permit the passage of moisture therethrough.

While leaks along the horizontal joints H are not as. common as those in the vertical or head joints, nevertheless, in some instances, it may be desired to provide the watertight joint of the present invention along these surfaces. Accordingly, the upper and lower mortar-receiving surfaces 26 of the brick or building unit can be provided with recesses similar to those formed in the end surfaces. A buildingunit so arranged is shown in Fig. 4, wherein the upper and lower faces are provided with dovetail grooves 24 which extend for the full length of the brick and have the walls 21 thereof form an angle A with the face 26. y

The grooves 24 are located at the same distance from the face of the building unit as are the end grooves, so that they intersect at the upper and lower edges of the unit. However, it is to be understood that the grooves maybe positioned in any suitable arrangement. If desired, a single groove may be utilized on the upper and lower surface which would be disposed between the recesses I4 on the ends of the building unit, and thus would not intersect with the end recesses.

The number and position of the recesses or grooves in the mortar-receiving surfaces of the unit will, of course, be dictated by the conditions to which the unit is to be subjected.

The recess, according to the preferred form of the invention, should be of such a depth and by the mortar moves in the direction to increase the pressure thereof against the walls of the recess and produce a bond therebetween to form a watertight joint.

3. A building unit having deep recesses formed in the end surfaces thereof to extend from the top to the bottom of said surfaces, at least portions of the walls of the recess forming an acute angle with the mortar-receiving surfaces which is less than the angle formed by a line representing the resultant movement of the quarter section of the joint and the center line of the mortar joint whereby said walls intercept-the mortar of the joint during movement thereof incident to the setting of the mortar and increase the pressure to produce a strong bond therebetween.

4. A building unit having mortar-receiving surfaces along the top, bottom and ends thereof,

width that a sufiicient mass of mortar will be located within the recess so as to have substantial movement to cause the face of the mortar to be moved relative to the wall and into pressing engagement therewith.

While the recess has been shown in Figs. 1 to 3 as being dovetail in shape, it, of course, may be of other shapes, such as that shown at Ma in Fig. 5, wherein the corners of the dovetail have been rounded so that the side walls Ha are reversed curves. A portion of the wall Ila, however, prsents a surface which is disposed with respect to face |6a so as to form the required angle A.

In the form of the invention shown in Fig. 6, a circular recess Mb is employed. In this construction, a portion of the wall "b will lie at an angle with respect to the face 16b so as to produce the required angle A.

In the forms of the invention shown in Figs. 5 and 6, the required angle A must be less than the angle formed by the resultant of movement of a quarter section of the joint and the center line of the joint, as in the form of the invention shown in Figs. 1 to 3. When this relation exists, a bond between the mortar and unit will be obtained which will insure a watertight joint.

Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

I claim:

1. A building unit having a mortar-receiving surface with a recess formed therein, at least portions of the walls of the recess forming an acute angle with the mortar-receiving surface which is less than the angle formed by a line representing the resultant movement of the quarter section of the joint and the center line of the mortar joint whereby said walls intercept the mortar of the joint during movement thereof incident to the setting of the mortar and increase the pressure to produce a strong bond therebetween and a sealed joint.

2. A building unit having mortar-receiving surfaces and dovetail recesses formed therein for the full length thereof, the walls of the recess forming an angle with the surface which is less than the angle formed by a line representing the resultant motion of the quarter section of the joint passing through the center of gravity of said quarter section and the center of the mortar joint and a line passing through the center of the mortar joint parallel with the surface, whereeach of said surfaces having mortar-receiving recesses formed therein, the walls of the recesses forming an angle with the surface which is less than the angle formed by a line representing the resultant movement of the quarter section of the mortar joint during setting thereof and the center line of the joint whereby the walls of the recesses intercept the moving mortar to increase the pressure therebetween incident to the setting of the mortar to produce a watertight joint.

5. In a masonry joint, the combination of a plurality of building units each having recesses along an adjoining face thereof in opposition to one another; and mortar located between the faces and filling the recesses to form a joint therebetween, the walls of the recess forming an acute angle with the face of the unit. said angle being less than the angle formed by a line representing the resultant motion of the quarter section of the joint and a line passing the center of the joint parallel to the face of the units, whereby the mortar in each recess in moving during setting toward the center of the joint will be pressed into engagement with the walls of the recess and form an intimate bond therewith to produce a watertight joint.

6. In a masonry joint, the combination of a plurality of building units having a dovetail recess along opposing faces thereof; and mortar positioned between the units and filling the recesses to form a joint therebetween, the angle of the walls of the recess with the face of the unit being less than the angle formed by a line passing through the center of mass of a quarter section of the joint and the center of the joint and a line passing the center of joint parallel to the face of the unit, whereby the mortar in each recess in moving during setting toward the center of the joint will be pressed into engagement with the walls of the recess and form an intimate bond therewith to produce a watertight joint.

7. In a masonry joint, the combination of a plurality of building units having substantially cylindrical recesses extending for the full length along the mortar-receiving faces thereof in opposition to one another; and mortar between i the units and filling the recesses to form a joint therebetween, at least a portion of the walls of the recesses forming an angle with the face of the unit less than the angle formed by a line passing through the center of mass of a quarter section of the joint and the center of the joint, and a line passing the center of joint parallel to the face of the unit, whereby said mortar, upon contracting, presses against the portion of the wall forming the angle with the face of the unit to produce a watertight joint therebetween,

8. The method of producing a watertight masonry joint, the steps of forming a recess in a mortar-receiving surface of the building units so that the walls of the recess form a predetermined angle with said surface for the joint to be made. and laying up the units with a mortar joint therebetween so that the units will be spaced a predetermined distance apart and the recesses will be filled with mortar whereby a line passing through the center of the joint and the center of gravity of the quarter section of the joint at the recess will form an angle with the center line of the joint which is greater than said predetermined angle, and setting the mortar to cause it 9. The method of producing a watertight masonry joint, the steps of forming a deep, broad recess in a mortar-receiving surface of building units so that the walls of the recess form a predetermined angle with said surface, and laying up the units with a mortar joint therebetween with the mortar filling the recesses in the units to provide a mass having substantial movement during the setting of the mortar, the joint being So proportioned that a line representing the resultant movement of each quarter section of the joint and the center line of the joint will form an angle which is greater than said predetermined angle whereby the moving mass of mortar will press to contract and press against the walls of the 5 against the walls of the recess and form a waterrecess and bond thereto to produce a watertight connection.

tight joint therewith.

AUGUST J. BOHN. 

